用相機拍攝的iOS裁剪圖像

Question

我正在使用相機（iOS 7,iPad mini）拍攝照片並將其裁剪爲正方形。我非常滿意從以下代碼中獲得的默認裁剪功能：

imagePickerController = [[UIImagePickerController alloc] init]; 
    imagePickerController.delegate = self; 
    imagePickerController.mediaTypes = @[(NSString *) kUTTypeImage]; 
    imagePickerController.allowsEditing = YES; 
    UIImage *image = info[UIImagePickerControllerEditedImage] 

它給了我一個平方疊加在我拍攝的圖像上。如果我放大，我可以將圖像平移一下。不過，我很驚訝，我無法上下移動圖像（沒有縮放），將裁剪矩形移到圖像上。如果我嘗試這樣做，它就會彈回到原來的位置。我錯過了什麼？還是僅僅缺少這個功能？

從這裏的許多問題來看，大多數人的回答都令人失望，「必須以自定義的方式完成」。

Answer 1

這是最簡單的方法（不需要重新實現UIImagePickerController）。首先，使用覆蓋圖使相機區域呈現正方形。這裏有一個例子3.5" 屏幕（你需要更新它爲iPhone 5的工作）：

UIImagePickerController *imagePickerController = [[UIImagePickerController alloc] init]; 
imagePickerController.sourceType = source; 

if (source == UIImagePickerControllerSourceTypeCamera) { 
    //Create camera overlay 
    CGRect f = imagePickerController.view.bounds; 
    f.size.height -= imagePickerController.navigationBar.bounds.size.height; 
    CGFloat barHeight = (f.size.height - f.size.width)/2; 
    UIGraphicsBeginImageContext(f.size); 
    [[UIColor colorWithWhite:0 alpha:.5] set]; 
    UIRectFillUsingBlendMode(CGRectMake(0, 0, f.size.width, barHeight), kCGBlendModeNormal); 
    UIRectFillUsingBlendMode(CGRectMake(0, f.size.height - barHeight, f.size.width, barHeight), kCGBlendModeNormal); 
    UIImage *overlayImage = UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext(); 

    UIImageView *overlayIV = [[UIImageView alloc] initWithFrame:f]; 
    overlayIV.image = overlayImage; 
    [imagePickerController.cameraOverlayView addSubview:overlayIV]; 
} 

imagePickerController.delegate = self; 
[self presentViewController:imagePickerController animated:YES completion:nil]; 

然後，你會得到一張圖片後，從的UIImagePickerController回來，這作物的方形像這樣的東西。！。

//Crop the image to a square 
CGSize imageSize = image.size; 
CGFloat width = imageSize.width; 
CGFloat height = imageSize.height; 
if (width != height) { 
    CGFloat newDimension = MIN(width, height); 
    CGFloat widthOffset = (width - newDimension)/2; 
    CGFloat heightOffset = (height - newDimension)/2; 
    UIGraphicsBeginImageContextWithOptions(CGSizeMake(newDimension, newDimension), NO, 0.); 
    [image drawAtPoint:CGPointMake(-widthOffset, -heightOffset) 
        blendMode:kCGBlendModeCopy 
         alpha:1.]; 
    image = UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext(); 
} 

這是目標C代碼